A longitudinal study of the relationship of physical activity to bone mineral accrual from adolescence to young adulthood

Baxter-Jones, Adam D.G.; Kontulainen, Saija; Faulkner, Robert A.; Bailey, D. A.

doi:10.1016/j.bone.2008.07.245

Cited by 169 publications

(146 citation statements)

References 30 publications

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“…(42) This is important because we have shown previously that body composition plays a major role in the prediction of BMC accrual in adolescence. (43) We also have shown previously in this cohort that physical activity plays a major role in predicting BMC accrual both in adolescence (15) and young adulthood (44) and that nutritional status plays an independent role in BMC accrual. (45) Comparisons of our cohort with other cohorts is problematic, but we have no reason to believe that this cohorts' nutrition and habitual physical activity patterns are significantly different from others.…”

Section: Discussionsupporting

confidence: 79%

Bone mineral accrual from 8 to 30 years of age: An estimation of peak bone mass

Baxter-Jones

Faulkner

Forwood

et al. 2011

Journal of Bone and Mineral Research

523

373

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Bone area (BA) and bone mineral content (BMC) were measured from childhood to young adulthood at the total body (TB), lumbar spine (LS), total hip (TH), and femoral neck (FN). BA and BMC values were expressed as a percentage of young-adult values to determine if and when values reached a plateau. Data were aligned on biological ages [years from peak height velocity (PHV)] to control for maturity. TB BA increased significantly from À4 to þ4 years from PHV, with TB BMC reaching a plateau, on average, 2 years later at þ6 years from PHV (equates to 18 and 20 years of age in girls and boys, respectively). LS BA increased significantly from À4 years from PHV to þ3 years from PHV, whereas LS BMC increased until þ4 from PHV. FN BA increased between À4 and þ1 years from PHV, with FN BMC reaching a plateau, on average, 1 year later at þ2 years from PHV. In the circumpubertal years (À2 to þ2 years from PHV): 39% of the young-adult BMC was accrued at the TB in both males and females; 43% and 46% was accrued in males and females at the LS and TH, respectively; 33% (males and females) was accrued at the FN. In summary, we provide strong evidence that BA plateaus 1 to 2 years earlier than BMC. Depending on the skeletal site, peak bone mass occurs by the end of the second or early in the third decade of life. The data substantiate the importance of the circumpubertal years for accruing bone mineral. ß

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Section: Discussionsupporting

confidence: 79%

Bone mineral accrual from 8 to 30 years of age: An estimation of peak bone mass

Baxter-Jones

Faulkner

Forwood

et al. 2011

Journal of Bone and Mineral Research

523

373

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“…mechanical loading | sarcopenia | osteoporosis P hysical exercise has widely recognized benefits on metabolic and skeletal health, and is routinely used as a nonpharmacologic intervention in therapeutic protocols for a variety of diseases (1,2). Decreases in the level of physical activity, for example in former athletes, can lead to progressive loss of bone (3).…”

mentioning

confidence: 99%

The myokine irisin increases cortical bone mass

Colaianni

Cuscito

Mongelli

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

387

367

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It is unclear how physical activity stimulates new bone synthesis. We explored whether irisin, a newly discovered myokine released upon physical activity, displays anabolic actions on the skeleton. Young male mice were injected with vehicle or recombinant irisin (r-irisin) at a low cumulative weekly dose of 100 µg kg(-1). We observed significant increases in cortical bone mass and strength, notably in cortical tissue mineral density, periosteal circumference, polar moment of inertia, and bending strength. This anabolic action was mediated primarily through the stimulation of bone formation, but with parallel notable reductions in osteoclast numbers. The trabecular compartment of the same bones was spared, as were vertebrae from the same mice. Higher irisin doses (3,500 µg kg(-1) per week) cause browning of adipose tissue; this was not seen with low-dose r-irisin. Expectedly, low-dose r-irisin modulated the skeletal genes, Opn and Sost, but not Ucp1 or Pparγ expression in white adipose tissue. In bone marrow stromal cell cultures, r-irisin rapidly phosphorylated Erk, and up-regulated Atf4, Runx2, Osx, Lrp5, β-catenin, Alp, and Col1a1; this is consistent with a direct receptor-mediated action to stimulate osteogenesis. We also noted that, although the irisin precursor Fndc5 was expressed abundantly in skeletal muscle, other sites, such as bone and brain, also expressed Fndc5, albeit at low levels. Furthermore, muscle fibers from r-irisin-injected mice displayed enhanced Fndc5 positivity, and irisin induced Fdnc5 mRNA expression in cultured myoblasts. Our data therefore highlight a previously unknown action of the myokine irisin, which may be the molecular entity responsible for muscle-bone connectivity

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“…1 Notably, it is extensively reported that physical exercise has beneficial effects on bone mineral density (BMD), in particular during childhood and adolescence. 2 In adult, decrease in physical activity may lead to a progressive loss of bone mineral content, raising the incidence of osteoporotic fractures. 3 Even worse, disuse and weightlessness can remarkably affect bone physiology: astronauts lose bone mass 10 times faster than women in early menopause; 4 patients in vegetative state have high bone turnover and low BMD, which translates into a clinically relevant problem, as 20% of these patients develop spontaneous fractures.…”

Section: Introductionmentioning

confidence: 99%

Role of Irisin on the bone–muscle functional unit

Colaianni

Grano

2015

BoneKEy Reports

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Irisin was originally recognized as a hormone-like myokine secreted as a product of fibronectin type III domain containing 5 from skeletal muscle in response to exercise both in mice and humans. The first role attributed to Irisin was its ability to induce trans-differentiation of white adipose tissue into brown, but we recently demonstrated that Irisin also has a central role in the control of bone mass, even at lower concentration than required to induce the browning response. Considering how physical exercise is important for the development of an efficient load-bearing skeleton, we can now consider this myokine as one of the molecules responsible for the positive correlation between exercise and healthy bone, linking to the well-established relationship between muscle and bone. Recombinant Irisin (r-Irisin), administered at low dose in young mice, increases cortical bone mineral density and positively modifies bone geometry. Irisin exerts its effect prevalently on osteoblast lineage by enhancing differentiation and activity of bone-forming cells, through the increase in activating transcription factor 4 expression. Low-dose r-Irisin also increases osteopontin and decreases sclerostin synthesis but did not affect Uncoupling protein 1 expression in white adipose tissue, whose upregulation is known to cause browning of fat, when Irisin is administered at a higher dose. These findings offer an explanation to the positive outcome on the skeleton triggered by skeletal muscle during physical activity and prove that the bone tissue is more sensitive than the adipose tissue to the Irisin action.

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A longitudinal study of the relationship of physical activity to bone mineral accrual from adolescence to young adulthood

Cited by 169 publications

References 30 publications

Bone mineral accrual from 8 to 30 years of age: An estimation of peak bone mass

Bone mineral accrual from 8 to 30 years of age: An estimation of peak bone mass

The myokine irisin increases cortical bone mass

Role of Irisin on the bone–muscle functional unit

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